Eternal Witness

When this creature enters, you may return target card from your graveyard to your hand.

Aesi, Tyrant of Gyre Strait

You may play an additional land on each of your turns.
Landfall — Whenever a land you control enters, you may draw a card.

Lulu, Stern Guardian

Whenever an opponent attacks you, choose target creature attacking you. Put a stun counter on that creature.
{3}{U}: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Omega, Heartless Evolution

Wave Cannon — When Omega enters, for each opponent, tap up to one target nonland permanent that opponent controls. Put X stun counters on each of those permanents and you gain X life, where X is the number of nonbasic lands you control. (If a permanent with a stun counter would become untapped, remove one from it instead.)

Dour Port-Mage

Whenever one or more other creatures you control leave the battlefield without dying, draw a card.
{1}{U}, {T}: Return another target creature you control to its owner's hand.

Evolution Sage

Landfall — Whenever a land you control enters, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Summon: Shiva

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I, II — Heavenly Strike — Tap target creature an opponent controls. Put a stun counter on it. (If a permanent with a stun counter would become untapped, remove one from it instead.)
III — Diamond Dust — Draw a card for each tapped creature your opponents control.

Starfield Vocalist

If a permanent entering the battlefield causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.
Warp {1}{U} (You may cast this card from your hand for its warp cost. Exile this creature at the beginning of the next end step, then you may cast it from exile on a later turn.)